Concrete slab joint construction



April 28, 1970 J. G. ELLIS CONCRETE SLAB JOINT CONSTRUCTION 2 Sheets-Sheet 1 Filed Oct. 11. 19s",

James 6. Ellis IN VENTOR.

April 70 J. G.ELL.-|S v 3,508,365

CONCRETE SLAB JOINT CONSTRUCTION Filed Oct. 11, 1967 I 2 Sheets$heet 2 A??? INVEN TOR. 30 42 BY w Maw United States Patent US. Cl. 52-169 Claims ABSTRACT OF THE DISCLOSURE A concrete slab key joint forming means adapted to be utilized in combination with a conventional concrete slab edge mold member which key joint forming means comprises an elongated sheet metal key joint forming strip adapted to be supported above sub-grade and below grade by a plurality of novel key joint strip positioning legs resting on the sub-grade and wherein the key joint forming strip is provided with a plurality of apertures for the through passage of reinforcing bars to be embedded within the concrete slab and wherein the reinforcing bars are nestingly received within the key joint forming strip so as to be readily accessible subsequent to casting of the female portion of the key joint and prior tothe casting of the male portion of the key joint contiguous therewith.

' The present invention relates to a novel concrete slab joint construction means and more particularly to a novel means of forming concrete slabs and the like with tongue and groove or key joints. More specifically, the present invention relates to the provision of a novel construction for a concrete slab key joint forming and supporting means adapted to remain embedded within adjoining cast keyed concrete slabs.

It is an object of the present invention to provide an improved concrete slab joint construction for the generally monolithic casting of concrete slabs by the provision of an improved key joint construction means.

Another object of the present invention is to provide an improved concrete slab key joint forming means which may be utilized in combination with conventionally utilized concrete slab edge forming molds so as to provide an inexpensive simple means of producing generally monolithic concrete slabs provided with tongue and groove key joints so as to provide a joint which generally precludes vertical displacement of adjoining keyed slab portions while permitting contraction.

A further object of the present invention is to provide an inexpensive expendable means of forming concrete slab key joints, which forming means remains with the joint formed thereby significantly reducing the over-all cost of forming concrete slab key joints.

Still another object of the present invention iss to provide an improved concrete slab key joint forming means comprising an elongated rigid female key joint portion forming means supported a predetermined distance from a'sub-grade upon which a key jointed concrete slab is to be cast and wherein the key joint forming elongated strip is supported by a plurality of leg members which rest upon the sub-grade and clampingly engage the key forming strip in such a manner whereby a conventional planar concrete slab edge form member may be placed in contiguous relation to the supported key forming strip so as to greatly facilitate the casting of a concrete slab with ICC alfemale key joint portion extending longitudinally therea ong.

Still another object of the present invention is to provide an improved key joint forming strip positioning and securing means which generally comprises a sheet metal stamping, generally of unitary construction, provided with means for clampingly engaging and positioning a key joint forming strip at a predetermined distance above a sub-grade and which key joint forming strip supporting means is further provided with integral detent means, to normally preclude dislodgement of the key forming strip therefrom under the influence of the weight of a concrete slurry being poured thereon and thereabout.

Still a further object of the present invention is to provide an improved method of casting concrete key joined slabs wherein the provision of an improved key joint forming means greatly facilitates the placement of reinforcing bars within the concrete slab being cast whereby a leg or clip holds the reinforcing bars in a key joint forming strip when the strip is being positioned and secured against a slab edge joint form whereby the expense associated with the construction of key jointed concrete slabs is significantly reduced.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being bad to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a perspective view of a conventional generally planar vertical concrete slab edge form illustrating an initial manipulative step associated with the utilization of a key joint forming member of the present invention utilized in combination therewith;

FIGURE 2 illustrates the operative positioning of a reinforcing bar positioning and supporting key joint'forming strip by a plurality of sub-grade supported key joint forming strip supporting and positioning legs which also lock the reinforcing bars within the key joint forming strip.

FIGURE 3 is an enlarged vertical cross-sectional view through one of the key joint forming strip supporting legs as seen substantially along the plane of line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged perspective view of the key joint forming strip positioning and supporting leg shown in FIGURES 2 and 3;

FIGURE 5 is a plan view of a unitary sheet metal stamping utilized to form the leg illustrated in FIG- URE 4;

FIGURE 6 is an enlarged transverse sectional view taken substantially along the plane of line 66 of FIG- URE 5;

FIGURE 7 is a perspective view of a concrete slab provided with a female key joint of utilization of the improved key joint forming means and method comprising the present invention, and further showing the manner in which reinforcing bars positioned and supported by facilitate the securement of additional reinforcing bars thereto thereby positioning and spacing the next reinforcing bar mat prior to the casting of a successive generally monolithic portion of a concrete slab.

Referring now in greater detail to the drawings and FIGURES 1 and 2 in particular, it will be seen that an improved concrete slab key joint forming means indicated generally at is illustrated as being utilized in combination with a conventional concrete slab edge form 12 comprising a generally L-shaped elongated metallic channel member having a base portion 14 resting on a sub-grade to be provided with a generally monolithic key joined concrete slab having a thickness generally corresponding to the dimension of a generally planar upstanding vertical edge forming portion 16 of the form 12.

The exemplary embodiment of the concrete slab key joint forming mean-s 10 includes an elongated keyway forming or mold strip indicated at 18 provided with longitudinally extending upper and lower coplanar portions 20 and 22 respectively and provided with a key deformation portion 24 interposed between and connected to the upper and lower planar portions 20 and 22 so as to comprise as will become more apparent hereinafter, the means of forming a female portion of a key joint. The keyway forming strip 18 is provided with apertures indicated generally at 26 in the vertically disposed portion of the key deformation portion 24 which apertures 26 are provided for the through passage of reinforcing and tie bars 28. It will be appreciated that the apertures 26 will vary in size, and spacing depending upon the desired placement and size of the reinforcing bars 28 utilized.

The key joint forming strip 18 is operatively positioned against the vertical surface 16 of the edge form 12 by key joint forming strip positioning means comprising a plurality of key joint forming strip positioning legs indicated generally at 30. The positioning legs are,

preferably, although not necessarily, of unitary construction and comprising a base portion 32 adapted to rest on a sub-grade to be provided with a concrete key jointed slab. The leg 30 further includes a generally vertically disposed upstanding portion 34 adapted to extend upwardly above the sub-grade on which the device rests and provided with a means of retaining the coplanar flanges 20 and 22 of the key joint forming strip 18. Toward this end, the upstanding portion 34 includes an inwardly struck lower strip portion retaining tab 36, such as formed by inwardly striking a portion of the member 34. A downwardly opening slot indicated at 38 and adapted to retain the upper flange 20 of the key forming strip 18 is formed by inwardly striking a portion of the member 34 to provide the upper strip portion retaining tab 41. As will be seen best from a consideration of FIG- URES 3 and 4, the upstanding portion 34 of the leg 30 is further provided with a stop tab 40, such as formed by inwardly striking a portion of the vertical leg portion 34 in a manner analogous to the formation of the tab 36 so as to provide a means of precluding displacement of the upper flange 20 from within the slot 38 under the influence of the weight of concrete impinging on the key deformation portion 24 of the strip 18 during pouring of the concrete slab. The key forming strip supporting leg 30 is preferably formed of a relatively non-corrodible sheet metal, such as galvanized steel for example and is preferably provided with a plurality of concave-convex deformations 42 to assist in stiffening the leg 30. The base portion 32 of the leg 30 is also provided with an aperture indicated at 44 for the reception of an anchor bar 46 such as comprising a short length of reinforcing rods which anchor 46 secures the key joint forming means 10 against the slab edge form 12.

The method of forming a concrete slab key joint utilizing the forming means 10 of the present invention comprises setting appropriate lengths of slab edge forms such as the form 12 on a prepared sub-grade and appropriately placing lengths of reinforcing bars 28 through the apertures 26 provided in the key forming strip 18 wherein the end portions of the reinforcing bars 28 which are ultimately to be tied to an adjoining slab are deformed so as to be nestingly received within the key deformation portion 24 of the strip 18 generally in a manner whereby the ends of two bars 28 overlap. The strip supporting legs 30 are then engaged to the strip 18 in overlying retaining relation to the overlapped ends of the bars 28 by passing the flange portion 20 between the tab 40 and the downwardly turned tab 41 and thence upwardly within the slot 38. By manually deforming the strip 18 or the leg 30 slightly, which it will be understood has a slight resiliency, the tab 36 will snap over the lower flange portion 22 of the key strip 18 thereby locking the strip 18 to the leg 30. The strip 18 which is. preferably formed of light gauge sheet metal with a plurality of the legs 30 and is then moved into contiguous relationship with the vertical portion 16 of the form .12, with the reinforcing bars nested and retained within the key deformation portion 24. The assembly is secured in the relationship shown in FIGURES 2 and 3 by the anchor bars 46. It will be appreciated that the height of the vertical portion of the leg 30 may be selectively varied during manufacture of the legs 30 to accommodate for varying thicknesses of key jointed slabs to the cast.

From a consideration of FIGURE 7 it will be seen that concrete has been poured within the form defined by the edge form 12 provided with the key joint forming means 10 so as to form a key jointed concrete slab portion 50 provided with a female key joint therein. It will be further seen in FIGURE 7 that the edge form 12 has been removed thereby showing how the expendable key forming strip 18 and strip supporting leg 30 initially remain substantially embedded within the slab 50. In addition, it will be seen that the deformed end portions of the reinforcing bars 28 still remain in the nested position within the key deformation portion 24 of the strip 18. From a consideration of FIGURE 8 it will be understood that the deformed portion of the reinforcing bars 28 have been manipulated, such as by use of a length of pipe telescopically placed over the base 28, to rebend, i.e. straighten, the bars, thus simultaneously tearing the upper portion of the leg 30 free of the key strip so that the bars 28 can project straight out from the key defor-i mation portion 24 so as to facilitate joining reinforcing bars, such as the bar 29, thereto. The bar 29 comprises a portion of a mat for the reinforcement for an adjoining slab, not shown, to be monolithically cast and thus keyed to the slab 50. From the foregoing it will be apparent that the present invention comprises an eflicient, simple relatively inexpensive method and means of forming key jointed concrete slabs.

The foregoing is considered as illustrative only of, the principles of the invention. Further since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operaion shown and described, and accordingly all suitable modifications and equivalents may be resorted to falling within the scope of the invention as claimed.

What is claimed as new is as follows: i

1. In combination with an elongated generally planar vertical concrete slab edge form, a key joint construction,

means comprising an elongated keyway mold strip having longitudinal upper and lower coplanar portions adapted;

to abut the concrete slab edge form, a key deformation portion on the keyway mold strip interposed between and connected to the upper and lower planar portions, keyway mold strip positioning means clampingly engaged with said keyway mold strip, said keyway mold strip positioning means comprising a plurality of keyway mold strip support legs of generally unitary construction, each of the said support legs having a generally horizontally disposed base portion adapted to rest on a prepared subgrade, each said support leg including a generally verti-' means on the upstanding portion of each support leg constructed and arranged to grippingly engage with the keyway mold strip.

2. The combination of claim 1 wherein said keyway mold strip supporting and retaining means of said upstanding portion of said mold strip positioning means comprises a downwardly opening slot defined by a keyway strip upper planar portion retaining tab adjacent the top portion of said upstanding portion so as to provide a means of retaining said upper planar portion of said keyway mold strip, and a keyway strip lower planar portion retaining tab adapted to retain said lower planar portion of said keyway mold strip.

3. The combination of claim 2 wherein said keyway mold strip supporting and retaining means includes a keyway strip upper planar portion detent tab carried by said upstanding portion of said support leg and positioned beneath said downwardly opening keyway strip upper planar portion retaining slot so as to normally preclude disengagement of said upper planar portion from said downwardly opening slot.

4. The combination of claim 3 wherein said support leg is formed of unitary sheet material and said upper and lower planar portion retaining tabs and said upper planar portion detent tab comprise inwardly struck portions of said upstanding portion of said support leg, said inwardly struck tabs being disposed on the same side of said upstanding portion as said base portion.

5. The combination of claim 4 wherein the juncture of said base and said upstanding portions of said support leg is provided with a reinforcing gusset means.

6. A key joint construction means comprising elongated keyway mold strip having longitudinal upper and lower coplanar portions adapted to abut a concrete slab edge form and provided with a key deformation portion interposed between and connected to the upper and lower planar portions, keyway mold strip positioning means clampingly engaged with said keyway mold strip, said keyway mold strip positioning means comprising a plurality of keyway mold strip support legs of generally unitary construction and having a base portion adapted to rest on a prepared sub-grade to be provided with a key jointed slab, said support leg including a generally vertically disposed upstanding portion integral with and generally normal to said base portion and a keyway mold strip supporting and retaining means on the upstanding portion constructed and arranged to grippingly engage with at least one of the coplanar portions of the keyway mold strip.

7. The combination of claim 6 wherein said keyway mold strip supporting and retaining means of said upstanding portion of said mold strip positioning means comprises a downwardly opening slot defined by a keyway strip upper planar portion retaining strip adjacent the top portion of said upstanding portion so as to provide a means of retaining said upper planar portion of said keyway mold strip, and a keyway strip lower planar portion retaining tabadapted to retain said lower planar portion of said keyway strip.

8. The combination of claim 7 wherein said keyway mold strip supporting and retaining means includes a keyway strip upper planar portion detent tab carried by said upstanding portion of said support leg and positioned beneath said downwardly opening keyway strip upper planar portion retaining slot so as to normally preclude disengagement of said upper planar portion from said downwardly opening slot.

9. The combination of claim 8 wherein said support leg is formed of unitary sheet material and said upper and lower planar portion retaining tabs and said upper planar portion detent tab comprise inwardly struck portions of said upstanding portion of said support leg, said inwardly struck tabs being disposed on the same side of said upstanding portion as said base portion.

10. The combination of claim 9 wherein the juncture of said base and said upstanding portions of said support leg is provided with a reinforcing gusset means.

References Cited UNITED STATES PATENTS 2,262,677 11/ 1941 Heltzel 94 --8 2,618,038 ll/l952 Stewart 25-131 3,343,329 9/1967 Pohutsky 52677 3,347,515 10/1967 White 2499 2,064,528 12/ 1936 Fischer 948 2,290,990 7/1942 Pagel 52735 HENRY C. SUTHERLAND, Primary Examiner J. L. RIDGILL, JR., Assistant Examiner US. Cl. X.R. 52689; 94-8 

